UE-40074

Modal dialogues appear offscreen when using monitors with different resolutions

Modal dialogues appear offscreen when using monitors with different resolutions

When using a monitor setup where both monitors have a large gap in resolution sizes and using UI scaling on Windows 10, the save dialogues that appear in the engine can appear offscreen in certain scenarios. This involves the main editor being on the Primary monitor and an asset editor of some sort being on the secondary monitor. Depending how much UI scaling is being used on the Primary monitor, this can appear offcenter or completely offscreen, making it inaccessible.

Regression?: No
This also occurred in 4.12 and 4.13

Steps to Reproduce

Get a setup where you have two monitors with the Primary being set to 3840x2160 and the Secondary set to 1920x1080 on Windows 10 and set the UI scaling of the Primary monitor to 150%. Be sure to sign out and back into Windows after doing this to apply the changes.

Open a new project

Create a new material

With the main editor window on the Primary monitor, move the Material Editor window to the secondary monitor and make it full screen

Add anything to the material editor (ex: Pull any node from the right side into the graph)

Close the Material Editor
Result: The dialogue that asks if you would like to save your changes appears either offscreen completely or at least off center.
Expected: The dialogue remains visible and in the middle of the screen.